I'm quite fond of killing characters. I like the ripples a good death sends through the story. Fake out deaths are way too common, most of mine will stay dead. Any time a character comes back they tend to be well foreshadowed (at least in my opinion, there's a piece I've got where a trio of brothers are unable to die, when killed they just wake up a period of time later, all three are deeply traumatized by it, the oldest in particular from having to patch his brothers up which I had been pretty heavy-handedly for 15chapters before "killing" one of them and I still had people not realising he was immortal when he came back) and they never come back entirely right (came back wrong tropes can be a hell of a lot of fun).
Almost anyone can die as long as it serves the plot. I get the most fun from giving terrible characters what they deserve, characters who are just turning from evil getting killed off just before they truly can, and innocent characters out of the blue because it's that kind of world and people just die (given my current world is full of soldiers and monsters this is very much a thing).
That said I'm really sensitive to deaths of characters I love in other works. I love it, but I hate it and will often be forced to fix the death via fanfiction. S1 of the K anime has a particularly fantastic one that gets me teary just thinking about it. One of my favourites that I actually rewatch every now and again has one of the villains turn on his mentor/father figure after the murder of his best friend, the anime plays it as "I don't care if it costs me my life if I can kill you and have revenge" while the manga takes it more as "I know it'll kill me trying to kill you like this and I don't care because I can't keep going without him". Tragic, they're my babies and it hurts, but I love it anyway.